AUTHOR=Shi Peng , Hua Wei , Htwe Yin Min , Zhang Dapeng , Li Jun , Wang Yong 

TITLE=Abscisic Acid Improves Linoleic Acid Accumulation Possibly by Promoting Expression of EgFAD2 and Other Fatty Acid Biosynthesis Genes in Oil Palm Mesocarp

JOURNAL=Frontiers in Plant Science

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2021.748130

DOI=10.3389/fpls.2021.748130

ISSN=1664-462X

ABSTRACT=<p>Abscisic acid plays an important role in fruit development. However, the effect of ABA on fatty acid biosynthesis in oil palm is still unknown. In this study, ABA treatments (CK, A1–A4) were applied to oil palm fruit at 16 WAP (weeks after pollination), and fatty acids in the mesocarp at 24 WAP were analyzed by GC-MS. Results showed that linoleic acid content under treatment A2 (20 μM ABA) was significantly higher (slightly increased by 8.33%) than the control. Therefore, mesocarp samples of A2, and the control at 16, 20, and 24 WAP was sampled for RNA-Seq. KEGG pathway enrichment analysis showed that 43 genes were differentially expressed in the fatty acid biosynthesis pathway, of which expression of <italic>EgFAD2</italic> (unigene 105050201) under 20 μM ABA treatment was 1.84-fold higher than in the control at 20 WAP. Further sequence analysis found that unigene 105050201 had more ABA-responsive elements (ABRE), complete conserved domains, and a C-terminal signaling motif among two <italic>FAD2</italic> copies. Furthermore, WGCNA and correlation analysis showed co-expression of <italic>EgFAD2</italic> (unigene 105050201) with transcription factors (TFs) (<italic>WRI1</italic>, <italic>AP2-EREBP</italic>, <italic>bZIP</italic>, <italic>bHLH</italic>, <italic>C2C2-Dof</italic>, <italic>MYB</italic>, <italic>NAC</italic>, and <italic>WRKY</italic>), ABA signaling genes (<italic>PYR</italic>, <italic>PP2C</italic>, <italic>SnRK</italic>, and <italic>ABI5</italic>), and other genes involved in fatty acid biosynthesis (<italic>FATA</italic>, <italic>FATB</italic>, <italic>LACS</italic>, <italic>SAD</italic>, <italic>Oleosins</italic>, and so on). These results indicated that ABA treatment promoted the expression of <italic>FAD2</italic> and other genes involved in fatty acid biosynthesis, which possibly resulted in the accumulation of linoleic acid. This study will be helpful for understanding the possible mechanisms through which ABA affects fatty acid biosynthesis and their accumulation in the mesocarp of oil palm.</p>